After building my sliding bevel and finding out they only cost about $8.00 from Masters I found this video (Probably through another uke builder) and decided I needed to do this. The cheapest one (cam clamp) I found locally cost just under $10.00 at my local bike store, so only do it if you have more money than sense lol.
A quick search of ebay gave me this:-
Road Bike Bicycle Seat Quick Release Binder Bolt Clamp Lever Silver for $1.89 US each at the time of writing.
It works well and I might find other uses for this kind of thing. I'm thinking of some luthier cam clamps, like the one in this video.
or for uses like this